Numerical simulation of ultrashort-pulse reflectometry(USPR)on EAST  

作　　者：俞潇烽 陈冉 李小良 朱逸伦 Calvin W DOMIER 阮行磊 黄泰豪 郭晋 林子钰 徐国盛 毛世峰 Neville C LUHMANN JR 叶民友 Xiaofeng YU;Ran CHEN;Xiaoliang LI;Yilun ZHU;Calvin W DOMIER;Xinglei RUAN;Taihao HUANG;Jin GUO;Ziyu LIN;Guosheng XU;Shifeng MAO;Neville C LUHMANN JR;Minyou YE(School of Nuclear Science and Technology,University of Science and Technology of China,Hefei 230026,People’s Republic of China;Institute of Plasma Physics,Chinese Academy of Sciences,Hefei 230031,People’s Republic of China;University of California at Davis,1 Shields Avenue,Davis CA 95616,United States of America)

机构地区：[1]School of Nuclear Science and Technology,University of Science and Technology of China,Hefei 230026,People’s Republic of China [2]Institute of Plasma Physics,Chinese Academy of Sciences,Hefei 230031,People’s Republic of China [3]University of California at Davis,1 Shields Avenue,Davis CA 95616,United States of America

出　　处：《Plasma Science and Technology》2023年第12期105-114,共10页等离子体科学和技术（英文版）

基　　金：supported by the National Magnetic Confinement Fusion Energy R&D Program of China(No.2019YFE03030004);National Natural Science Foundation of China(No.12005144)。

摘　　要：The microwave reflectometer is a popular non-intrusive plasma density diagnostic instrument on tokamaks that provides centimeter and millisecond level resolution.The ultrashort-pulse reflectometer(USPR)achieves plasma density measurement by emitting a chirped wave containing a broadband signal and measuring the time of flight from different frequency components.A USPR system is currently being built on EAST(Experimental Advanced Superconducting Tokamak)to meet the needs of diagnostic of the pedestal density evolution,such as high-frequency small edge-localized modes.In order to predict the density reconstruction of the EAST USPR system,this work presents a numerical simulation study of the beam propagation of the chirped wave of extraordinary waves(X-mode)in the plasma based on Python.The electron density profile has been successfully reconstructed by the reflection signal interpretation.The small gap between the right-hand cut-off layer and the electron cyclotron resonance layer,due to the low plasma density on the plasma edge,causes unexpected leakage from the transmitting microwave beam to the pedestal and the core region.This kind of‘tunneling’effect will cause the reflected signal to have energy loss in the low-frequency band.The study also discusses the influence of the poloidal magnetic field on the reflected signal.The spatial variation of the poloidal magnetic field will lead to the conversion between extraordinary(X)waves and ordinary(O)waves,which leads to energy loss in the reflected signals.The simulation results show that the‘tunneling’effect and the O-X mode conversion effect have little effect on the EAST USPR system.Therefore,the currently designed transmit power meets the working requirements.

关 键 词：REFLECTOMETER pedestal density profile beam mode conversion 

分 类 号：TL631.24[核科学技术—核技术及应用]